In the beginning, Paradox launched Cities Skylines without trams. Then they finally came with the Mass Transit update, but with no real tram avenue possibility. Almost every city in the world where the trams runs in the streets. They have street avenues where the trams runs in the middle. So!
A user calling himself Fluxtrance, have made a fantastic map for Cities Skylines. He streamed on 28th of February. The island, the cities and everything is so well done. I am blown away. Finishing Rhinestone Island Live Beginners should Watch this Here he describes about how he made this map.